title: A large prospective study of risk factors for adenocarcinomas and malignant carcinoid tumors of the small intestine.
abstract: OBJECTIVE
  Small intestinal cancer is increasing in the U.S.A, yet little is known about its etiology. Our aim was to prospectively evaluate risk factors for this malignancy by the two main histologic subtypes (adenocarcinomas and carcinoids).
  
  
  METHODS
  Hazard ratios and 95% confidence intervals (CI) were estimated for all incident small intestinal cancers (n = 237), adenocarcinomas (n = 84), and malignant carcinoids (n = 124), by demographic and lifestyle factors among 498,376 men and women.
  
  
  RESULTS
  Age was the only risk factor for adenocarcinomas (HR for ≥ 65 vs. 50-55 years = 3.12, 95% CI 1.33, 7.31). Age (HR for ≥ 65 vs. 50-55 years = 3.31, 95% CI 1.51, 7.28), male sex (HR = 1.44, 95% CI 1.01, 2.05), body mass index (BMI, HR for ≥ 35 vs. 18.5-< 25 kg/m2 = 1.95, 95% CI 1.06, 3.58), and current menopausal hormone therapy use (HR = 1.94, 95% CI 1.07, 3.50) were positively associated with malignant carcinoids. A family history of any cancer or colorectal cancer (HR = 1.42, 95% CI 0.99, 2.03; 1.61, 0.97, 2.65, respectively), or a personal history of colorectal polyps (HR = 1.51, 95% CI 0.92, 2.46) produced elevated, but not statistically significant, risks for malignant carcinoids. Race, education, diabetes, smoking, physical activity, and alcohol intake were not associated with either histologic subtype.
  
  
  CONCLUSIONS
  Risk factors differed according to cancer subtype; only age was associated with adenocarcinomas, whereas age, male sex, BMI, and menopausal hormone therapy use were positively associated with malignant carcinoids.
authors.affiliation: Division of Cancer Epidemiology and Genetics (DCEG), Department of Health and Human Services (DHHS), National Cancer Institute (NCI), National Institutes of Health (NIH), 6120 Executive Blvd, Rockville, MD 20852, USA. crossa@mail.nih.gov
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Cross
authors.forename: Albert R
authors.initials: AR
authors.lastname: Hollenbeck
authors.forename: Yikyung
authors.initials: Y
authors.lastname: Park
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology*; D000368:Aged; D002276:Carcinoid Tumor / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007414:Intestinal Neoplasms / Q000175:diagnosis / Q000453:epidemiology*; D007421:Intestine, Small / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology